Observation, Inference, Prediction, and Hypothesis PDF

Observation, Inference, Prediction, and Hypothesis ​ Observation: The act of noticing or perceiving something through the senses. Example: "The sky is dark." ​ Inference: A conclusion drawn based on evidence and reasoning, not directly observed. Example: "It is going to rain because t...

Observation, Inference, Prediction, and Hypothesis ​ Observation: The act of noticing or perceiving something through the senses. Example: "The sky is dark." ​ Inference: A conclusion drawn based on evidence and reasoning, not directly observed. Example: "It is going to rain because the sky is cloudy and dark." ​ Prediction: A statement about what will happen in the future based on observations and inferences. Example: "It will rain tomorrow." ​ Hypothesis: A testable statement or educated guess about the relationship between variables. Example: "If the sky is dark, then it will rain." Qualitative vs. Quantitative Observations ​ Qualitative Observation: Descriptive observations using the senses. Example: "The star is bright and yellow." ​ Quantitative Observation: Observations based on measurements or numerical data. Example: "The star is 10 light-years away." Celestial Bodies ​ Stars: Massive balls of gas, primarily hydrogen and helium, undergoing nuclear fusion to emit light and heat. They vary in size, temperature, and color. ​ Planets: Celestial bodies that orbit stars, like the Earth, composed mostly of rock, gas, or ice, and are spherical in shape. ​ Satellites (Moons): Natural or artificial bodies that orbit planets. Example: The Moon orbits Earth. ​ Comets: Icy bodies that, when close to the Sun, release gas and dust in a glowing tail. ​ Asteroids: Small rocky bodies that orbit the Sun, primarily in the asteroid belt between Mars and Jupiter. ​ Meteors: Small rocks or particles that burn up upon entering a planet’s atmosphere, creating a streak of light. ​ Meteorites: The remnants of meteors that reach the Earth's surface. ​ Galaxies: Large collections of stars, dust, gas, and dark matter, bound together by gravity. Properties of Light ​ Emission: When a substance emits light, usually due to heat or an electrical charge. Example: A glowing light bulb. ​ Reflection: When light bounces off a surface. Example: A mirror reflecting your image. ​ Absorption: When a surface takes in light energy. Example: A black shirt absorbing sunlight. ​ Conversion: The transformation of light into other forms of energy, like heat.  ​ Refraction: The bending of light when it passes from one medium to another. Example: A straw in water looks bent due to refraction. ​ Dispersion: The separation of light into its component colors. Example: A prism splitting white light into a rainbow. Prism Behavior: When light is refracted through a prism, it bends, with shorter wavelengths (blue, violet) bending more than longer wavelengths (red, orange), resulting in a spectrum. The visible colors in order are: red, orange, yellow, green, blue, indigo, and violet. Color and Light: White light consists of all visible wavelengths, while black is the absence of light. The color of an object depends on which wavelengths it reflects; for example, a red apple reflects red light and absorbs other colors. Evidence of Light Behavior: ​ Straight-Line Travel: Light casts sharp shadows, indicating it travels in straight lines. ​ Wave Nature: Interference patterns from the double-slit experiment show light behaves like a wave. ​ Particle Nature: The photoelectric effect shows light acts like a stream of particles (photons). ​ Refraction: Light bends when entering a different medium, as seen with a pencil in water. ​ Diffraction: Light bending around edges, showing it behaves like a wave. Waves, Wave Equation, and Scientific Notation ​ Wave Properties: The parts of a wave include the crest (highest point), trough (lowest point), wavelength (distance between two crests), amplitude (height of the wave), and frequency (how often the wave passes a point). ​ Wave Equation: v=f⋅λv = f \cdot \lambdav=f⋅λ, where: ○​ vvv = speed of the wave (m/s) ○​ fff = frequency (Hz) ○​ λ\lambdaλ = wavelength (m) ​ Conversions: Scientific notation is used to simplify large or small numbers, e.g., 45,000,00045,000,00045,000,000 becomes 4.5×1074.5 \times 10^74.5×107, and 0.000000670.000000670.00000067 becomes 6.7×10−76.7 \times 10^{-7}6.7×10−7. Electromagnetic Spectrum and Spectroscopy ​ EM Waves: The electromagnetic spectrum includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. The order from longest wavelength to shortest is: ○​ Radio waves > Microwaves > Infrared > Visible light > Ultraviolet > X-rays > Gamma rays.  ​ Ionizing vs. Non-Ionizing Radiation: Ionizing radiation (e.g., X-rays, gamma rays) has enough energy to remove electrons from atoms, which can damage DNA. Non-ionizing radiation (e.g., radio waves, visible light) lacks this energy. ​ Spectra Types: ○​ Continuous Spectrum: A full spectrum of light without gaps. ○​ Absorption Spectrum: Light absorbed by elements in a gas, leaving dark lines. ○​ Emission Spectrum: Light emitted by elements, showing bright lines. ​ Emission and Absorption Spectra in Stars: The unique lines in absorption and emission spectra reveal the chemical composition of stars, including hydrogen, helium, and other elements. Doppler Effect and Big Bang Theory ​ Doppler Effect: A change in wavelength or frequency of a wave due to the motion of the source or observer. When the source moves towards the observer, the waves compress (blue shift), and when it moves away, the waves stretch (red shift). ​ Redshift and Blueshift: Evidence of the Doppler effect in light, where redshift indicates an object moving away (like distant galaxies) and blueshift indicates an object moving toward us. ​ Hubble’s Law: The observation that galaxies are moving away from us, with their speed proportional to their distance, supports the idea of an expanding universe (Big Bang Theory). ​ Big Bang Evidence: 1.​ Redshift of Galaxies: The observation that galaxies are moving away from us. 2.​ Cosmic Microwave Background Radiation (CMBR): Discovered by Penzias and Wilson, CMBR is residual radiation from the Big Bang. 3.​ Abundance of Elements: The relative amounts of hydrogen and helium in the universe suggest they were formed during nucleosynthesis in the early universe. Stellar Evolution ​ Star Formation: Stars form from a nebula (a cloud of gas and dust) which collapses under gravity, forming a protostar. ​ Nuclear Fusion: In stars, hydrogen fuses into helium, releasing energy (E = mc²). ​ Main Sequence Stars: Stars like the Sun are in a stable phase where gravitational force and fusion pressure are in balance. ​ Nucleosynthesis: Elements up to iron are formed in stars, and heavier elements are created in supernovae. Atomic Structure and Isotopes ​ Atom Structure: An atom consists of protons and neutrons in the nucleus and electrons orbiting the nucleus. ​ Isotopes: Atoms of the same element with different numbers of neutrons. They have the same chemical properties but different masses. ​ Radioactive Decay: ○​ Alpha Decay: Releases 2 protons and 2 neutrons. ○​ Beta Decay: A neutron becomes a proton, releasing an electron. ○​ Gamma Decay: Releases high-energy electromagnetic radiation. ​ Half-life: The time it takes for half of a sample of a radioactive substance to decay.